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2332. Photosynthetic induction in Eucalyptus urograndis seedlings and cuttings measured by an open photoacoustic cell
- Creator:
- Barja, P. R., Mansanares, A. M., da Silva, E. C., Magalhães, A. C. N., and Alves, P. L. C. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- Multiple languages
- Description:
- Photosynthetic induction in leaves of four-month-old Eucalyptus urograndis seedlings and of cuttings obtained from adult trees that were previously dark-adapted was studied by the in vivo and in situ Open Photoacoustic Cell Technique. Results for the gas exchange component of the photoacoustic (PA) signal were interpreted considering that the gas uptake component would have a phase angle nearly opposite to that of the oxygen evolution component. By subtracting the thermal component from the total PA signal, we studied the competition between gas uptake and oxygen evolution during the photosynthetic induction. Seedlings presented a net oxygen evolution prior to cuttings, but cuttings reached a higher steady-state photosynthetic activity. The chlorophyll (Chl) a/b ratio and the Chl fluorescence induction characteristic Fv/Fm were significantly higher for cuttings, while there was no difference between samples in stomata density and leaf thickness. Thus the differences in PA signals of seedlings and cuttings are associated to differences between the photosystem 2 antenna systems of these samples. and P. R. Barja ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2333. Photosynthetic light and carbon dioxide response of the invasive tree, Vochysia divergens Pohl, to experimental flooding and shading
- Creator:
- Dalmolin, A. C., Dalmagro, H. J., Lobo, F. de A., Antunes Jr., M. Z., Ortíz, C. E. R., and Vourlitis, G. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, Brazilian Pantanal, CO2 and light-response curves, ecophysiology, invasive plants, tropical wetlands, 2, and 581
- Language:
- Multiple languages
- Description:
- Vochysia divergens Pohl is considered to be a flood-adapted, light-demanding pioneer species that has been invading grasslands of the Brazilian Pantanal. In these areas, a successful invasion requires an ability to tolerate physiologically wide fluctuations in surface hydrology and shading induced by a dense cover of grasses and other vegetation. We evaluated how flooding and shading affected the photosynthetic performance of V. divergens saplings by measuring light-saturated gas exchange (net photosynthetic rate, PN; stomatal conductance, gs), and intercellular CO2 (PN/Ci) and photosynthetic photon flux density (PN/PPFD) response curves over a 61-d field experiment. Shading and flooding reduced significantly light-saturated PN and gs and affected multiple aspects of the leaf gas exchange response of V. divergens to variations in PPFD and CO2. Flooding influenced the physiology of this species more than shading. Given the success of V. divergens at invading and expanding in seasonally flooded areas of the Pantanal, the results were surprising and highlighted the physiological ability of this species to tolerate suboptimal conditions. However, the consistently higher light-saturated PN and gs under nonflooded conditions suggested that the invasive success of V. divergens might not be related to its physiological potential during flooding, but to situations, when flooding recedes during the dry season and soil water availability is adequate. and A. C. Dalmolin ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2334. Photosynthetic light response in three carnivorous plant species: Drosera rotundifolia, D. capensis and Sarracenia leucophylla
- Creator:
- Bruzzese, B. M., Bowler, R., Massicotte, H. B., and Fredeen, A. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, carnivorous plants, Drosera, photosynthesis, respiration, Sarracenia, and sundews
- Language:
- Multiple languages
- Description:
- Photosynthetic properties of carnivorous plants have not been well characterized and the extent to which photosynthesis contributes to carbon gain in most carnivorous plants is also largely unknown. We investigated the photosynthetic light response in three carnivorous plant species, Drosera rotundifolia L. (sundew; circumpolar and native to northern British Columbia, Canada), Sarracenia leucophylla Rafin. ('pitcher-plant'; S.E. United States), and D. capensis L. (sundew; Cape Peninsula, South Africa), using portable gas-exchange systems to explore the capacity for photosynthetic carbon gain in carnivorous plant species. Maximal photosynthetic rates (1.32-2.22 μmol m-2 s-1 on a leaf area basis) and saturating light intensities (100 to 200 μmol PAR m-2 s-1) were both low in all species and comparable to shade plants. Field or greenhouse-grown D. rotundifolia had the highest rates of photosynthesis among the three species examined. Dark respiration, ranging from -1.44 (S. leucophylla) to -3.32 (D. rotundifolia) μmol m-2 s-1 was high in comparison to photosynthesis in the species examined. Across greenhouse-grown plants, photosynthetic light compensation points scaled with light-saturated photosynthetic rates. An analysis of gas-exchange and growth data for greenhouse-grown D. capensis plants suggests that photosynthesis can account for all plant carbon gain in this species. and B. M. Bruzzese ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2335. Photosynthetic limitation of similar-height Cryptomeria japonica trees growing at different rates
- Creator:
- Tange, T., Someya, M., Norisada, M., and Masumori, M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, PN-Ci curve, stable carbon isotope ratio, water potential, 2, and 58
- Language:
- Multiple languages
- Description:
- We compared light-saturated photosynthetic rates and their stomatal limitations among Cryptomeria japonica trees with a similar height but different current growth rates. Although slow-growing trees had a lower stomatal conductance and a higher carbon isotope ratio in shoots, the stomatal limitations in photosynthesis were not different. Large mesophyll CO2 diffusion resistance contributed to the low photosynthetic rate of the slow-growing trees., T. Tange ... [et al.]., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2336. Photosynthetic limitations caused by different rates of water-deficit induction in Glycine max and Vigna unguiculata
- Creator:
- Bertolli, S. C., Rapchan, G. L., and Souza, G. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, cowpea, photosynthesis, rapid and slow water-deficit induction, recovery, soybean, 2, and 58
- Language:
- Multiple languages
- Description:
- Plants are constantly subjected to variations in their surrounding environment, which affect their functioning in different ways. The influence of environmental factors on the physiology of plants depends on several factors including the intensity, duration and frequency of the variation of the external stimulus. Water deficit is one of the main limiting factors for agricultural production worldwide and affects many physiological processes in plants. The aim of this study was to analyse the effects of different rates of induced water deficit on the leaf photosynthetic responses of soybean (Glycine max L.) and cowpea (Vigna unguiculata L.). The plants were subjected to two types of water deficit induction: a rapid induction (RD) by which detached leaves were dehydrated by the exposure to air under controlled conditions and a slow induction (SD) by suspending irrigation under greenhouse conditions. The leaf gas exchange, chlorophyll (Chl) a fluorescence, and relative water content (RWC) were analysed throughout the water-deficit induction. V. unguiculata and G. max demonstrated similar dehydration as the soil water percentage declined under SD, with V. unguiculata showing a greater stomatal sensitivity to reductions in the RWC. V. unguiculata plants were more sensitive to water deficit, as determined by all of the physiological parameters when subjected to RD, and the net photosynthetic rate (PN) was sharply reduced in the early stages of dehydration. After the plants exposed to the SD treatment were rehydrated, V. unguiculata recovered 65% of the PN in relation to the values measured under the control conditions (initial watering state), whereas G. max recovered only 10% of the PN. Thus, the better stomatal control of V. unguiculata could enable the maintenance of the RWC and a more efficient recovery of the PN than G. max., S. C. Bertolli, G. L. Rapchan, and G..M. Souza., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2337. Photosynthetic net O2 evolution enhancement as a sign of acclimation to phosphorus deficiency in bean (Phaseolus vulgaris L.) leaves
- Creator:
- Kozłowska-Szerenos, B., Jarosz, A., and Maleszewski, S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Mehler reaction, photosynthetic net O2 evolution, Phaseolus vulgaris, phosphorus deficiency, photorespiration, and quantum requirement
- Language:
- Multiple languages
- Description:
- Primary leaves of bean (Phaseolus vulgaris L.) seedlings cultivated for 14 days in a growth chamber on complete (control) and phosphate deficient (-P) Knop liquid medium were used for measurements. The -P leaves were smaller and showed an increased specific leaf area (SLA). Their inorganic phosphate (Pi) concentration was considerably lowered. They did not show any significant changes in chlorophyll (Chl) (a + b) concentration and in their net CO2 assimilation rate when it was estimated under the conditions close to those of the seedlings growth. Light response curves of photosynthetic net O2 evolution (P NO2) of the leaves for the irradiation range up to 500 μmol(photon) m-2 s-1 were determined, using the leaf-disc Clark oxygen electrode. The measurements were taken under high CO2 concentration of about 1 % and O2 concentrations of 21 % or lowered to about 3 % at the beginning of measurement. The results obtained at 21 % O2 and the irradiations close to or higher than those used during the seedlings growth revealed the phosphorus stress suppressive effect on the leaf net O2 evolution, however, no such effect was observed at lower irradiations. Other estimated parameters of P NO2 such as: apparent quantum requirement (QRA) and light compensation point (LCP) for the control and -P leaves were similar. However, with a high irradiation and lowered O2 concentration the rate of P NO2 for the -P leaves was markedly higher than that for the control, in relation to both the leaf area and leaf fresh mass. This difference also disappeared at low irradiations, but the estimated reduced QRA values indicate, under those conditions, the increased yield of photosynthetic light reaction, especially in the -P leaves. The presented results confirm the suggestion that during the initial phase of insufficient phosphate feeding the acclimations in the light phase of photosynthesis, both structural and functional appear. They correspond, probably, to the increased energy costs of carbon assimilation under phosphorus stress, e.g. connected with raised difficulties in phosphate uptake and turnover and enhanced photorespiration. Under the experimental conditions especially advantageous for the dark phase of photosynthesis (saturating CO2 and PAR, low O2 concentration), those acclimations may be manifested as an enhancement of photosynthetic net O2 evolution. and B. Kozłowska-Szerenos, A. Jarosz, S. Maleszewski.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2338. Photosynthetic nitrogen- and water-use efficiency of acacia and eucalypt seedlings as afforestation species
- Creator:
- Novriyanti, E., Watanabe, M., Makoto, K., Takeda, T., Hashidoko, Y., and Koike, T.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, afforestation, fast growing species, photosynthetic nitrogen-use efficiency, photosynthetic rate, photosynthetic water-use efficiency, 2, and 58
- Language:
- Multiple languages
- Description:
- The ecophysiological traits of acacia and eucalypt are important in assessing their suitability for afforestation. We measured the gas-exchange rate, the leaf dry mass per area (LMA) and the leaf nitrogen content of two acacia and four eucalypt species. Relative to the eucalypts, the acacias had lower leaf net photosynthetic rate (PN), lower photosynthetic nitrogen-use efficiency (PNUE), higher water-use efficiency (WUE), higher LMA and higher leaf nitrogen per unit area (N area). No clear differences were observed within or between genera in the maximum rate of carboxylation (Vcmax) or the maximum rate of electron transport (Jmax), although these parameters tended to be higher in eucalypts. PNUE and LMA were negatively correlated. We conclude that acacias with higher LMA do not allocate nitrogen efficiently to photosynthetic system, explaining why their PN and PNUE were lower than in eucalypts., E. Novriyanti ... [et al.]., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2339. Photosynthetic nutrient use efficiency, nodule activity and solute accumulation ín drought stressed alfalfa plants
- Creator:
- Antolín, M. C. and Sánchez-Díaz, M.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Effect of temporary drought on the photosynthetic characteristics, the photosynthetic nutrient-use efficiency (PNUE, PPUE), the water-use efficiency (WUE), acetylene reduction nodule activity (ARA) and the solute accumulation has been examined in nodulated alfalfa plants. The plants were subjected to moderate or severe cycles of drought (drought-recovery). Growth decreased markedly imder the water deficit, but no significant differences were found between either level of drought. As stress progressed, the plants developed higher root/shoot ratios than Controls. ARA declined progressively during water deficit treatments and upon rewatering no recovery was observed. PNUE and PPUE markedly decreased, whereas WUE increaseď in drought treated plants. Proline and inorganic cations (K, Ca, Mg) concentrations were always higher in drought-stressed plants, but sugar (TSS) content increased only in roots and nodules. Hence, imder cyclic drought nodulated alfalfa plants adjusted osmotically and achieved an improved WUE, which suggested an enhanced drought tolerance.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2340. Photosynthetic organisms and excess of metals
- Creator:
- Bertrand, M. and Poirier, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chloroplast, oxidative stress, photosynthesis, thylakoid membrane, and xanthophyll cycle
- Language:
- Multiple languages
- Description:
- When cells get metals in small excess, mechanisms of avoidance occur, such as exclusion, sequestration, or compartmentation. When the excess reaches sub-lethal concentrations, the oxidative stress, that toxic metals trigger, leads to persistent active oxygen species. Biomolecules are then destroyed and metabolism is highly disturbed. At the chloroplast level, changes in pigment content and lipid peroxidation are observed. The disorganized thylakoids impair the photosynthetic efficiency. The Calvin cycle is also less efficient and the photosynthetic organism grows slowly. When an essential metal is given together with a harmful one, the damages are less severe than with the toxic element alone. Combined metals and phytochelatins may act against metal toxicity. and M. Bertrand, I. Poirier.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public